A fluorescent lighting fixture housing includes a space for housing a ballast transformer, a metal reflector, tube socket members and wiring between the ballast transformer and the tube sockets. Conventionally, these housings (commonly called xe2x80x9ctrofersxe2x80x9d because they hold 2-4 fluorescent tubes) have been made out of sheet metal to convey heat generated by conventional heating of the filaments, ballast transformers and the heating from the plasma in the gas. This heating requires that the fixture be spaced from wood and other flammable structures using, in many cases, chains, hooks, etc., which suspend the fluorescent fixture from a ceiling, for example, which also allows cooling air to circulate and cool the fixture. In addition, these prior art fixtures require the use of heat resistant wire. Moreover, in most cases a metal housing is required to be conductive so as to provide an electrical ground to avoid shock hazards due to high voltage.
For the following reasons a standard fluorescent fixture should have ground:
1. A grounded metal housing of a predetermined size and gauge acts as a xe2x80x9cheat sinkxe2x80x9d for the ballast.
2. A grounded metal reflector with the lamps installed within about xc2xdxe2x80x3 of the reflector.
3. The ballast must be an integral part of the fixture.
4. The wiring in the fixture must be of at least #12 gauge and covered with high temperature insulation (over 95xc2x0 C.).
5. The inner space between the xe2x80x9cdrop ceilingxe2x80x9d and the structural ceiling must be ample enough to dissipate the heat from the fixture (from 2xe2x80x2 to 3xe2x80x2 average).
6. Power to the fixture must be supplied by a 3-wire system, 12 gauge or better, with a ground (bonded).
7. The metal fixture should have enough area of contact with the air to dissipate the heat.
8. Standard systems are xe2x80x9cground plane systems.xe2x80x9d
An object of the present invention is to provide a fluorescent lighting fixture and system which has a housing made of plastic.
Another object of the invention is to provide a fluorescent lighting fixture of the xe2x80x9ctroferxe2x80x9d type which is significantly cooler and as a result may be safely mounted directly on a ceiling.
Still another object of the invention is to provide a fluorescent lighting fixture and system which is ballast-free, significantly cooler in operation than prior art fixtures, and a fluorescent lighting fixture which is significantly less hazardous and thus safer from fire and high-voltage hazards.
Another object of the invention is to provide a lighting fixture of the trofer type which is shallow and of less volume than prior art trofers.
A fluorescent lighting fixture includes a plastic or non-conductive housing, preferably made of a thermoplastic resin, sockets for fluorescent tubes and an alternating current square-wave alternating voltage source (sometimes hereinafter called xe2x80x9csquare-wave driverxe2x80x9d or xe2x80x9cdriverxe2x80x9d) for driving the fluorescent tubes. In one embodiment, the square-wave driver is thin (not requiring a large heavy ballast transformer) and can be mounted by screws or an adhesive on the housing or carried in a slot molded or formed in the non-conductive housing. In another embodiment, since the driver is small and does not require a ballast transformer, it can be mounted in a light switch housing. In this case, since the current and voltage levels are low due to the improved efficiency of driving the fluorescent lamps or tubes with the high frequency alternating square waves supplied by the driver as described in my above-identified application, smaller gauge wires and less insulation can, if desired, be used. A conventional light diffuser may be mounted in the housing to diffuse the light from the lamps.
Features of a Plastic Fixture (Trofer), Driver and Lamp Array According to the Invention
1. Lamps can be driven by individual drivers, i.e. integral to the sockets or integral to the lamp. Or the lamps can be connected in series to the appropriate capacity driver in any numbers, odd or even.
2. The driver could be integral to the fixture or can be non-integral, mounted on a remote location, i.e. the switch assembly.
3. No grounded metal reflector is needed.
4. No clearance from combustible materials needed.
5. No heat release area between the finish ceiling and the structural ceiling needed.
6. No bonded ground is needed, no xe2x80x9cground wire.xe2x80x9d
7. No reinforcing of the finish ceiling is needed, due to low weight.